A trailer posted on YouTube yesterday revealed the first details of Overkill Software and Valve's co-developed follow-up to Overkill's downloadable heist simulator, Payday: The Heist. The video confirms rumors that the game will serve as a pre-outbreak prequel to the original Left 4 Dead.

Overkill and Valve announced that they're working together to make a new Payday that connects to Valve's zombie series. Rumors that the game was a prequel to the original picked up during E3.

"Follow up" might not actually be completely accurate. Though the title implies that the game is a stand-alone release, it's possible that No Mercy may be an expansion to the original Payday.

The name No Mercy refers to game's setting, Mercy Hospital, a location from the original Left 4 Dead. Though details are scarce, the trailer implies that the heist you perform may  lead to an apocalyptic zombie outbreak.

Personally, I'm a little offended that Valve and Overkill didn't go with our title, Zombies and Robbers, but I'll settle for a catastrophic world-ending heist experience.

[Via Shacknews]